Crossword Genius

Without warning Sue and old Alf explode (3,2,1,6)

Ross

I believe the answer is:

all of a sudden

'without warning' is the definition.
(I've seen this before)

'sue and old alf explode' is the wordplay.
'explode' is an anagram indicator.
'sue'+'and'+'old'+'alf'='sueandoldalf'
'sueandoldalf' anagrammed gives 'ALL OF A SUDDEN'.

(Other definitions for all of a sudden that I've seen before include "abruptly" , "Without warning" , "Quickly and unexpectedly" , "In an unexpected manner" .)

I've seen this clue in the Sydney Morning Herald.
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